Split GfxState animation operations

docs/remake-architecture-and-roadmap.md

@@ -612,6 +612,12 @@ do not mix mechanical moves with semantic changes.
    into `engine/Age.Engine/Model/GfxState.RetainedObjects.cs`. Cross-domain reset/persistence, animation, and
    presentation sampling retain direct access through the sealed partial class; runtime validation remains green.
 
+   The fourth bounded `GfxState` split moved shared animation-clock state, object color/source-cell/matrix/cyclic
+   channels, animation control and forced completion, and interpolation helpers into
+   `engine/Age.Engine/Model/GfxState.Animation.cs`. Presentation diagnostics, dirty-reason accounting, transition
+   queues, and visible-scene sampling consume the moved state through the sealed partial class; runtime validation
+   remains green.
+
    **Gate:** no externally visible behavior or command changes; generated artifacts are byte-identical where
    deterministic, and the corresponding engine, Python, Godot, and corpus validations remain green after
    each domain move.
@@ -983,7 +989,7 @@ layer's rendering diverges from ADV; save layout.
 ## 8. Immediate next step
 Continue step 2 of the **codebase consolidation** maintenance slice: behavior-neutral physical splits backed
 by the tracked launcher and layered validation driver. With the planned `Main` and `GodotAdvHost` domains
-isolated and the first three `GfxState` domains separated, move animation ownership next, preserving public types,
-commands, and generated output.
+isolated and the first four `GfxState` domains separated, move presentation ownership next, preserving public
+types, commands, and generated output.
 Concrete playthrough blockers may still preempt this bounded maintenance work; the consolidation effort does
 not replace Phase B gameplay validation or the open cross-platform gates.